Enter the travel length (m) and the slope into the Calculator. The calculator will evaluate the Time of Concentration. 

Time of Concentration Formula

tc = .0078*(L^..77/S^..385)


  • tc is the Time of Concentration (minutes)
  • L is the travel length (m)
  • S is the slope

How to Calculate Time of Concentration?

The following steps outline how to calculate the Time of Concentration.

  1. First, determine the travel length (m). 
  2. Next, determine the slope. 
  3. Next, gather the formula from above = tc = .0078*(L^.77/S^.385).
  4. Finally, calculate the Time of Concentration.
  5. After inserting the variables and calculating the result, check your answer with the calculator above.

Example Problem : 

Use the following variables as an example problem to test your knowledge.

travel length (m) = 9

slope = 10